Performance, carcass characteristics and immune response of Japanese quails to different levels of Mentha piperita L. powder

This study aimed to investigate the effects of different levels of peppermint (Mentha piperita L.) powder on performance, carcass characteristics and immune system of Japanese quail. For this purpose, 200 one-day-old quail chicks were used in a completely randomized design with four treatments and five replicates and 10 birds per replicate. The experimental treatments consisted of four levels of peppermint (0.0, 0.25, 0.5 and 0.75%). The consumption of 0.5 and 0.75% peppermint powder significantly reduced the severity of respiratory burst (P0.05). Different levels of peppermint powder caused to decreased antibody production against SRBC and humoral immune suppression (P0.05). Moreover, there were no significant differences between the treatments for carcass characteristics, internal organ weights and length and weight of different parts of the intestine (P>0.05). Thus, according to enhancement of cellular immune responses by peppermint powder, the use of peppermint powder is recommended during the viral illness (such as Newcastle, bronchitis and influenza) or intracellular parasite infection (such as coccidiosis).